Posted online on December 22, 2003 on www.jco.org Read Study One Read Study Two Obesity is known to increase the risk of breast, colorectal, and endometrial cancer. Now, two new studies suggest that obesity can also increase the risk of aggressive prostate cancer, particularly for black men.Both studies examined the relationship between obesity and prostate cancer recurrence in large samples of prostate cancer patients who had undergone surgery to remove the prostate - a procedure called radical prostatectomy.The studies found that obese men with prostate cancer were more likely to have aggressive tumors and to have their cancer return after surgery compared to men of normal weight or those who are overweight but not obese. Although more research is needed, the findings suggest that men may be able to modify their risk of aggressive prostate cancer by maintaining a healthy weight before they are diagnosed with the disease.While obesity rates in the general adult population are similar among black and white men, both studies found that obese patients in the study groups were more likely to be black. This finding may help explain why black men with prostate cancer generally have more aggressive tumors and lower survival rates compared to whites.The first study, which involved 3,162 prostate cancer patients, found that black men were more likely to be obese (27% versus 18% of white men), have higher cancer recurrence rates, and more aggressive disease.The second study, which involved 1,106 patients, found that moderately and severely obese men had a 60% risk of their cancer returning within 3 years. In this study, 31% of black men were obese, compared to 21% of white men.Researchers from both studies suggest that hormones and proteins found in body fat may cause prostate tumors to grow faster and more aggressively in obese men.What Does This Mean For Patients?These studies found that men may be able to reduce their risk of aggressive prostate cancer by maintaining a healthy weight. In addition, prostate cancer patients can limit the possibility that they develop more aggressive prostate tumors by maintaining a normal body weight.